Influent distribution means for tanks



p 1, 1964 w. F. JOHNSTON NFLUENT DISTRIBUTION MEANS FOR TANKS Filed Jan.16, 1961 FIG. I.

United States Patent 3,147,221 INFLUENT DISTRIBUTION MEANS FOR TANKSWilliam F. Johnston, Milwaukee, Wis., assignor to Chain Belt Company,Milwaukee, Wis., a corporation of Wisconsin Filed Jan. 16, 1961, Ser.No. 82,837 1 Claim. (Cl. 210-519) This invention relates to influentdistribution means for the introduction of a suspension into a tank forsettling or flotation separation of the suspended material. The feed isdirected against one or more dished baflles to be spread over theinfluent end Wall of the tank within artificial boundaries for each ofthe jets to prevent their interaction. The boundaries and theequalization of the flow eflected within the boundaries of each jetprovide a very significant improvement in the flow and distributionpattern so that the flow moves from said wall and the length of the tankwith a uniform velocity front for maximum separation efliciency.

Each dished battle is in effect set in a square recess formed by theboundaries and the end wall of the tank. Due to the mechanicalproper-ties of the water, e.g. its viscosity and mass, a practical limitof about seven feet square has been found for the size of each recessand a depth of only six inches is generally adequate. That is, therequired bafiie means providing the boundaries need be only about sixinches wide and need only project that distance into the tank.

The collector mechanism for the separation tank generally comprisesdrive chains along each side wall which support and move flights orplows which extend the width of the tank. Accordingly, it is or may beuneconomical to build such tanks less than about fourteen feet wide.Since the flights must be relatively rigid, light weight andreplaceable, certain woods such as cedar or redwood are usually used buttheir maximum unsupported length is generally limited to about twentyfeet. Such flights and other economic factors have generally limited thepractical width of the tanks to that distance. Accordingly, the presentinvention contemplates between two and four recesses for the usual tank.

Each recess should be about square so that a small tank of fourteen footwidth with two recesses would have a flow-through zone between six andseven feet deep. This may be too great for this size of tank and may bereadily reduced by using three recesses which might be up to five andone-half feet high. Other dimensions of such a tank and others are shownin the following table of typical tank sizes.

In the above cases the dished baflles have a diameter about one inchlarger than that of the inlet pipes and, as shown, each recess is formedby baflle means projecting from the inlet wall of the tank although therecesses can also be readily formed directly in the wall of the tank,particularly if the tank wall is of concrete.

A single header or distribution channel (trough) is connected to theseveral pipes ahead of each battle to provide the initial distributionof the flow.

The principal object of the invention is to provide an economicaleflicient and clog-free inlet structure. The present invention isintended for A.P.I. (American Petroleum Institute) oil-water separationtanks and also sewage 3,147,221 Patented Sept. 1, 1964 treatment tankswhich require a distribution means which is easy to maintain, requiresno cleaning or infrequent cleaning, and does not require several inchesof hydraulic head to operate.

The drawings furnished herewith illustrate the best mode of carrying outthe invention as presently contemplated and set forth hereinafter.

In the drawings:

FIGURE 1 is vertical longitudinal cross-section of a tank intended forthe separation of oil and water which may also include some sand orother settleable material requiring removal. The tank and apparatus areillustrated diagrammatically;

FIG. 2 is a section taken on line 22 of FIGURE 1 and shows the recessesand battles in front elevation;

FIG. 3 is a plan view of the inlet end of the tank shown in FIGURE 1;and

FIG. 4 is an enlarged cross-section taken through the center-line of oneof the inlet pipes. The section shows the wall of the tank and otherparts as they would be made of steel.

The tank 1 shown in the drawings includes the side walls 2 and end walls3 and 4. The top of end wall 3 forms a weir 5 over which the clear waterflows into the box 6 to which the discharge pipe 7 is connected. Weir 5serves to maintain a given liquid level in the tank.

Tank 1 also includes the trough 8 located adjacent to end wall 4 and theflat floor 9 having a slope downwardly to trough 8. The collectormechanism operating over floor 9 includes the chain 10 which carries theseries of flight or scrapers 11 extending the width of the tank. Chain10 operates over the sprockets 12 and 13 and the upper drive is drivenby the motor unit 15 disposed above the tank and connected to sprocket14- by the chain drive 16.

The oil collection mechanism includes the chain 19 which carries theseries of flights or scrapers 20 so that the oil is pushed toward and upthe beach 21 and into the receiving trough 22 located near the end wall3 of tank 1. Chain 19 operates over the sprockets 23 and 24 which latteris driven by the motor drive unit 25 and drive chain 26.

Trough 22 and the baflle 27 extending downwardly from the trough arespaced from end wall 3 and floor 9 of the tank to provide a submergedoutlet from the lower separation zone 31 of the tank.

The present invention provides a submerged inlet by which the water andoil suspension is introduced into the tank to flow with a uniformvelocity front through the lower separation zone 30 and beneath theupper clarification zone 31 of the tank. The two zones referred to maybe of different depths or of generally the same depth as shown by thebroken line 32 denoting their common boundary.

The cross-header 33 at the inlet end of the tank is provided with thecentral flanged fitting 34 by which the header is connected to deliverypipe 35. Header 33 also includes the series of fittings 36 connectingthe header with the corresponding fittings of each of the inlet pipes37.

Each inlet pipe 37 extends through wall 4 of tank 1 and may project intothe tank a small distance or none at all as shown. Generally, each pipe37 should be straight and depending on the size of header 33, ofsuflicient length so that the flow from the orifice or open end of thepipe is in the form of a uniform, straight jet of a circular flowpattern. The open end of each pipe should also be between one and oneand one-half diameters from the corresponding dished baflie 38.

The baflies 38 may be supported by a single cross bar 39, secured atopposite ends to wall 2 of the tank as shown, or individually suportedas by brackets, not shown, attached a to the wall 4 of the tank abovepipe 37 and joined to the bafille on the convex side or rear of thebafiile.

As previously described, the bafiies 38 serve to spread the jets fromthe corresponding pipes 37, but do not assure the desired uniformvelocity front. According to the present invention, the desired uniformflow section or velocity front is provided by the horizontal andvertical bafles 40 and 41 in combination with pipes 37 and bafiles 38.As shown, bafiles 40 and 41 project from wall 4 to form a series ofsquare recesses extending across the width of the tank and symmetricallyarranged about pipes 37 and baffies 38 so that each pipe 37 and baffle38 is at the geometric center of a recess. The side walls 2 may beincluded with baffle 40 and 41 or separate wall or bafi le means, notshown, may be provided to define the ends of the series of squares ateach side of the tank.

As will be seen in the drawings, the recesses are only approximately ofequal height and width so that their dimensions correspond with that ofthe fiow through section and particularly the tank Width which isgenerally selected for the space available or other considerations. Inthat regard, also, the use of the squares greatly reduces the number ofinlet pipes required for effective inlet control. This means that eachpipe may be larger to improve the distribution of the flow in header 33to each of such fewer and larger pipes.

Each recess defines the limit of spread of each jet over the wall of thetank so that the flow upon leaving the wall 4 of the tank has What mightbe considered a waffie pattern enclosing a series of voids at the backside of or behind each baffle 33. However, according to dye tests thevoids are filled as the flow moves forward and from somewhere within twofeet of baffles 38, the flow then continues with remarkable uniformityover the length of the tank.

The invention may also be used in sewage treatment tanks as well where awell controlled and defined fiowthrough pattern is desired for theflotation or settling or material having a specific gravity very nearlythat of water. Particularly in tanks of concrete construction, therectangular or square recesses may be formed directly in the inlet Walland setting each pipe 37 and baffle 38 at the center of a recess.

The several recesses are arranged and dimensioned to provide the desiredtotal cross-section of the flow through the tank and the bafiles aregenerally not required at the side Walls of the tank. Where the flow isto move directly over the floor of the tank, as in a tank for flotationseparation only, no lower bafile means would be required. Also, if theflow-through zone is to extend to the water surface no upper bafflemeans would ordinarily be required.

The invention is, of course, not to be considered limited to tankswithin the range of sizes mentioned. Similarly, the depth of theflow-through zone for thickeners might be less than four feet in manycases.

Various modes of carrying out the invention are contemplated as withinthe scope of the following claim particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

In a rectangular tank for the flotation of suspended solids in the upperzone of the tank and requiring introduction and passage of the feed intoand through a lower flow through zone of the tank with a minimum of headloss and no disturbing eddy currents, said tank including a floor, inletand outlet end walls and adjacent side Walls and having a bafile spacedfrom the outlet end wall and floor of the tank and defining an outletapproximately corresponding to the cross-section of said lower flowthrough Zone; baffle means comprising relatively thin, flat platesprojecting from the inlet end wall and toward the outlet end wall andwith the side walls of the tank defining a series of rectangular,shallow recesses having their openings facing said tank outlet andtogether corresponding to the cross-section of said lower flow throughzone, a distribution header outside of the tank and having a pluralityof pipes extending through the inlet end Wall of the tank such that onepipe extends into each recess at the geomertic center of the recess andhas its open end within the recess and facing the outlet of the tank,and a dished bafile within each recess supported by the tank and spacedfrom the end of the pipe within the respective recess and having itsconcave side facing the end of the pipe whereby the feed entering thetank from each said pipe flows radially of each said pipes over theinlet wall within the recess to the surrounding bafile means, the platesbetween dished bafiles preventing any interaction of such flow fromadjacent pipes and the several bafile means being disposed such that theborders of the jets from the pipes are fully expanded to the dimensionsof the flow through zone crosssection prior to flowing toward the outletend of the tank and as described providing the same with a substantiallyuniform velocity front corresponding to the cross-section of said lowerflow through zone.

References Cited in the file of this patent UNITED STATES PATENTS1,374,625 Allen Apr. 12, 1921 1,931,988 Hromadka Oct. 24, 1933 2,059,844Boosey Nov. 3, 1936 2,525,936 Owen Oct. 17, 1950 2,702,124 Stengel Feb.15, 1955 2,708,520 Dallas May 17, 1955 2,973,866 Genter et a1. Mar. 7,1961

